The P-Answer-State Header Extension to the Session Initiation Protocol for the Open Mobile Alliance Push to Talk over Cellular
RFC 4964
Document | Type |
RFC - Informational
(September 2007; No errata)
Was draft-allen-sipping-poc-p-answer-state-header (individual in rai area)
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Authors | Jan Holm , Andrew Allen , Thomas Hallin | ||
Last updated | 2015-10-14 | ||
Replaces | draft-allen-sipping-poc-p-headers | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4964 (Informational) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Jon Peterson | ||
Send notices to | fluffy@cisco.com, dean.willis@softarmor.com |
Network Working Group A. Allen, Ed. Request for Comments: 4964 Research in Motion (RIM) Category: Informational J. Holm Ericsson T. Hallin Motorola September 2007 The P-Answer-State Header Extension to the Session Initiation Protocol for the Open Mobile Alliance Push to Talk over Cellular Status of This Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Abstract This document describes a private Session Initiation Protocol (SIP) header (P-header) used by the Open Mobile Alliance (OMA) for Push to talk over Cellular (PoC) along with its applicability, which is limited to the OMA PoC application. The P-Answer-State header is used for indicating the answering mode of the handset, which is particular to the PoC application. Allen, et al. Informational [Page 1] RFC 4964 The P-Answer-State Header September 2007 Table of Contents 1. Introduction ....................................................3 2. Overall Applicability ...........................................3 3. Terminology .....................................................3 4. Background for the Extension ....................................4 5. Overview ........................................................5 6. The P-Answer-State Header .......................................6 6.1. Requirements ...............................................8 6.2. Alternatives Considered ....................................8 6.3. Applicability Statement for the P-Answer-State Header ......9 6.4. Usage of the P-Answer-State Header ........................10 6.4.1. Procedures at the UA (Terminal) ....................11 6.4.2. Procedures at the UA (PTT Server) ..................11 6.4.3. Procedures at the Proxy Server .....................14 7. Formal Syntax ..................................................14 7.1. P-Answer-State Header Syntax ..............................14 7.2. Table of the New Header ...................................14 8. Example Usage Session Flows ....................................15 8.1. Pre-Arranged Group Call Using On-Demand Session ...........15 8.2. 1-1 Call Using Pre-Established Session ....................21 9. Security Considerations ........................................28 10. IANA Considerations ...........................................28 10.1. Registration of Header Fields ............................28 11. Acknowledgements ..............................................29 12. References ....................................................29 12.1. Normative References .....................................29 12.2. Informative References ...................................30 Allen, et al. Informational [Page 2] RFC 4964 The P-Answer-State Header September 2007 1. Introduction The Open Mobile Alliance (OMA) (http://www.openmobilealliance.org) is specifying the Push to talk Over Cellular (PoC) service where SIP is the protocol used to establish half-duplex media sessions across different participants. This document describes a private extension to address specific requirements of the PoC service and may not be applicable to the general Internet. The PoC service allows a SIP User Agent (UA) (PoC terminal) to establish a session to one or more SIP UAs simultaneously, usually initiated by the initiating user pushing a button. OMA has defined a collection of very stringent requirements in support of the PoC service. In order to provide the user with a satisfactory experience, the initial session establishment (from the time the user presses the button to the time they get an indication to speak) must be minimized. 2. Overall Applicability The SIP extension specified in this document makes certain assumptions regarding network topology and the existence of transitive trust. These assumptions are generally NOT APPLICABLE in the Internet as a whole. The mechanism specified here was designed to satisfy the requirements specified by the Open Mobile Alliance for Push to talk over Cellular for which either no general-purpose solution was found, where insufficient operational experience was available to understand if a general solution is needed, or where a more general solution is not yet mature. For more details about theShow full document text